1. Field of the Invention
The present invention relates to an electronic still camera capable of recording and regenerating information from a recording medium by coding and decoding image data and sound data relative to a photographed image.
2. Description of the Related Art
Japanese Patent Application Laying Open (KOKAI) No. 2-280484 shows an electronic still camera capable of recording and regenerating a picture image and a sound. As shown in this camera, a sound is stored to a sound memory while a continuous photographing mode is set and a continuous photographing operation is performed. The stored sound is recorded to a recording medium such that this sound corresponds to a picture image continuously photographed. The continuously photographed picture image and the sound during the continuous photographing operation are simultaneously regenerated from the recording medium so that an atmosphere at a photographing time can be sufficiently reproduced in this regeneration.
In this electronic still camera, a regenerated image such as a moving picture image can be obtained by continuously performing the photographing operation at a high speed. For example, an NTSC signal is obtained if a field image is recorded and regenerated every 1/60 second. When an image is recorded to the recording medium, it is necessary to take measures for recording sound data to the recording medium in synchronization with image data.
For example, the recording medium used for the electronic still camera is constructed by a memory card. A memory region of this memory card is divided into plural memory units each having a predetermined memory capacity such that images having plural kinds of image sizes are efficiently stored to the memory card.
For example, Japanese Patent Application Laying Open (KOKAI) No. 3-187690 shows an apparatus for recording and regenerating an image so as to increase recording and regenerating speeds of data recorded and regenerated from the memory card used for the electronic still camera. In this apparatus, a central processing unit (CPU) designates a top address in a first memory unit when all plural memory units having image data to be written or read from the memory card are continued. Thereafter, an address is designated by sequentially incrementing the top address by an address register arranged within the memory card. A switching operation of the memory units normally performed is omitted by stopping operations of an address generator and a data counter by the central processing unit (CPU). Thus, when all the plural memory units having image data to be written or read from the memory card are continued, the image data can be written or read from the memory card at a high speed.
In the above image recording-regenerating apparatus, when the image data as a file are recorded to the memory card and are regenerated from the memory card, it is necessary to read and write the image data by the central processing unit (CPU) using software. Accordingly, a processing time of the image recording-regenerating apparatus is increased so that no moving image can be recorded and regenerated in real time.
In the electronic still camera, when an image is recorded to the memory card as a recording medium, it is necessary to take measures for recording sound data and image data to the recording medium at a high speed.
Japanese Patent Application Laying Open (KOKAI) No. 3-265287 shows an electronic still camera device. In this electronic still camera device, a semiconductor memory has a region for recording information indicative of an empty unit recording region to be first recorded when image data are recorded. Thus, the empty unit recording region is retrieved for a short time.
However, when data are recorded in this electronic still camera device, a central processing unit (CPU) must write header information by using software. Therefore, a processing time of the central processing unit (CPU) is increased and no moving image can be recorded to the recording medium in real time.
The electronic still camera is mainly used at present as a device for inputting image and sound data to an information equipment. For example, Japanese Patent Application Laying Open (KOKAI) No. 4-212582 proposes a technique for directly inputting image data of an electronic camera to a personal computer and performing an editing operation of the image data, etc. without using any adapter, etc.
However, no adaptability (or affinity) between the present electronic still camera and the information equipment is good. Accordingly, it is necessary to use hardware and software for an interface (I/F).
The following problems are concretely caused.
(1) Image formats used for the information equipment are different from each other in accordance with application programs. When no format of an image file recorded by the electronic still camera is suitable for an application, it is necessary to make a program for converting the file format.
(2) The electronic still camera of a standard type is designed such that an image is regenerated and seen on the screen of a television such as NTSC, etc. Accordingly, no aspect ratio of a pixel is equal to "1". Therefore, when such a recorded file is regenerated by the information equipment such as a personal computer as it is, an image of the recorded file is defaced and is not clearly displayed.
(3) When image data are directly transferred to the information equipment through a recording medium interface (I/F), no image data can be normally displayed on a side of the information equipment when no synchronous position of the image data is transferred to the information equipment.